Motor control for maintaining the tension of positively pulled warp threads in warp looms



Jan. 16, 1968 W. LIEBCHEN 3,364,403

MOTOR CONTROL FOR MAINTAINING THE TENSION OF POSITIVELY PULLED WARP THREADS IN WARP LOOMS Original Filed Nov. 4, 1964 2 Sheets-$heet 1 Jnven/or:

W W WW Jan. 16, 1968 w LIEBCHEN 3,364,403

MOTOR CONTROL FOR MAINTAINING THE TENSION OF POSITIVELY PULLED WARP THREADS IN WARP LOOMS Original Filed Nov. 4, 1964 2 Sheets-Sheet 2 --55?@ 593 57a Q93 I INVENTOR MWLOEMHR 0686/1541,

BY J J ATTOR EYIS United States Patent Ofiice 3,364,403 Patented Jan. 16, 1968 1 Claim. 61. 318--6) This application is a continuation of application Ser. No. 408,974, filed Nov. 4, 1964, now abandoned.

The invention relates to a method of controlling the winding-off speed of positively pulled warp threads in warp looms, especially the pile threads in plush looms, and to an apparatus for carrying out the process.

Arrangements for the positive feeding-off of threads in warp looms by positive turning of the warp beam by means of a special drive are well known. They have not however been used to any great extent in practice because of the difiiculties in maintaining the speed of rotation of the beam such as to produce a constant thread feed. In simple looms in general a positive thread pay-out is not used.

Increased work loads however lead in many cases to unacceptably high thread tensions in the customary arrangement for drawing off threads from the beam. Especially in the manufacture of cut plush, the substantially larger pile beam cannot be moved by the pull of the pile threads alone, if under high work loads breakage of the thread is to be completely avoided. This requires in the positive turning of the pile beam a continuous adjust ment of the turning speed to agree with the actual rate of withdrawal of thread.

It is the purpose of the present. invention to provide a system which in a simple and reliable manner allows a regulation of the thread take-off speed by constant adjustment of the speed of the warp or pile beam. According to the invention this purpose is accomplished by utilizing the angular position of a known type of thread tensioner for controlling the speed of rotation of the drive of the warp or pile beam.

In an advantageous arrangement of the invention, an apparatus for carrying out this process has devices for supplying impulses controlled by the swinging of a tension balance in opposite directions, these impulses being supplied to the control arrangement for changing the driving speed of the beam. According to a further feature of the invention, the arrangement for the changing of the driving speed is advantageously an infinitely variable transmission.

An especially advantageous modification of the invention consists in using electric limit switches, which operate the positioning or control motor of the infinitely vari' able transmission. The latter is preferably a repulsion motor.

It is further desirable to provide timing mechanism for lengthening the interval of timing of the impulse produced, for example an electrical relay with means for automatically holding the switch contacts closed for a limited time. By this arrangement each impulse produces a certain movement of the positioning member, and assures quiet operation of the arrangement without appreciable excessive impulses.

Further objects and advantages of the invention will appear more fully from the following description, particularly when taken in conjunction with the accompanying drawings which form a part thereof.

In the drawings:

FIG. 1 shows in perspective and schematically an arrangement for carrying out the invention; and

FIG. 2 is a wiring diagram.

FIG. 1 shows one end of a warp beam 11, mounted on a shaft 12 rotatable in a bearing 13 carried by the machine frame. The wrap threads 14 are, in the usual way, drawn off from the warp beam 11 and pass through a conventional tension balance 15, which is carried by a shaft 17 journalled at 16 in the machine frame and urged by spring 16a in a counterclockwise direction, to the needle eyes of the machine, which are not shown.

The beam can also be the pile beam of a cut plush loom, the pile threads being led in a similar manner over a tension balance to the different needles. Because the pile beam, as far as its diameter is concerned, does not differ appreciably from the warp beam carrying the threads for the base fabric, the construction to be described is satisfactory in all particulars also for the control of the winding-olf speed of pile threads in plush looms, so that there are no additional requirements whether only the pile beam or only the warp beam or only individual warp beams are to be positively driven.

On the end of shaft 12 of the warp beam 11 is a sprocket 18, which is drivably connected by chain 19 with a sprocket 21 on an intermediate shaft 22. The intermediate shaft 22 also carries a pinion 23 which engages with an intermediate pinion 24 which is also in engagement with a pinion 27 arranged on the driven shaft 25 of the reducing gear 26. The reducing gear takes its power through the sprockets 28, 29 connected by chain 31 from the cam shaft 32 of the loom, by which the tongues of the eye needles of the machine are in the conventional way moved out and in or up and down.

The pinions 23, 24, 27 form a changeable ratio drive, whose transmission ratio can be changed by changing the pinion 23. The intermediate pinion 24 is carried by a lever 33 which is journalled on the drive shaft 25 so that it can be adjusted to any selected diameter of the pinion 23. In the engaged position of the pinions 23-, 24, the segment lever 33 is fastened by a bolt 35 passing through a coaxial slot 34 in the lever 33 and mounted stationarily on the housing of the reducing gear 26.

Of course the transmission ratio of the drive between the cam shaft 32 and the warp beam shaft 12, that is the chain drive 29, 31, 28 of the reducing gear 26, the variable ratio drive 27, 24, 23 and the chain drive 21, 19, 18 are so selected and determined that the warp beam 11 at a predetermined speed of the cam shaft 32 is turned at a speed corresponding to the mean requirement of the warp thread lengths to be unwound.

As the diameter of the body of yarn wound on the warp beam changes with the progressive drawing off of the threads, it is necessary to change the speed of rotation of the beam, in order to keep the thread speed constant. Other factors also such as a variation in the tension with which the yarn is wound on the warp beam may also influence the required operational speed of the machine. In order to balance these variations, the gear 26 is formed as an infinitely variable transmission. Such devices are well known. For changing the transmission ratio there is provided on the transmission housing a shaft 37, which carries a worm gear 38. A worm 39 on a stationarily journalled auxiliary shaft 41 meshes with worm gear 38. Auxiliary shaft 41 is connected by a worm gear 42 and a worm 43 to be driven by an electric motor 44 which may be constituted as a reversing motor.

The shaft 17 of the tension detector extends outwardly beyond the bearing 16. This extension carries two levers 45, 46 clamped on it which cooperate with electrical limit switches 47, 48, respectively, mounted on the machine frame. The limit switches 47, 48 and the levers 45, 46 are arranged in relation to each other and in relation to the tension balance so that, in the normal median position of the tension balance 15, the two curved levers lie between the switches 47, 48. As, in consequence of an increasing thread tension, the tension balance 15- swings clockwise through a given angle (position shown in the drawing) the curved lever 45 operates the limit switch 47. Conversely with decreasing tension as a result of swinging of the member counterclockwise the curved lever 46 operates the limit switch 48.

Lines 49, 51 lead from the limit switches 47, 48 to a relay switch 52 which is connected in the input line 53, 54 of motor 44. By the relay switch 52 motor 44, upon operation of one of the limit switches 47, 48, is connected to current source S in such a way that, depending upon which end switch has produced the switching, the motor is turned in such a direction that the transmission ratio of the reducing gear is changed in a sense opposite to that of the connected lever 47 or 48, so as to vary the tension of the thread and restore the member 15 to its normal position.

In order, when only short operations of the limit switches 47, 48 occur (which, in view of the constant slight back and forth swinging of the tension balance 15, are likely to exceed its mean swinging range), to avoid connecting the motor for only a short time with the source of current, without causing the motor to run properly and the reduction gear to be changed, the switch relay 52 is provided with an automatic arrangement for holding the control switches closed for a predetermined period each time one of the limit switches is closed. Such a circuit is shown in FIG. 2.

Three-phase line 53 having conductors 53a, 53b, 53c connects switch box 52 to alternating current source S, while line 54 having three conductors 54a, 54b, 54c connects switch box 52 to motor 44. Within the switch box are conventional three-pole switches 56, 57 arranged in parallel for connecting conductors 53a, 53b, 53c to conductors 54a, 54b, 540 so as to energize motor 44 in opposite directions. Switches 56, 57 are closed by energization of coils 56a, 57a respectively.

A line 58 connects one terminal of each of coils 56a, 57a through rectifier 59 and variable resistance 61, controlled by knob 55, to conductor 53b. Lines 49a, 51a connect lines 49, 51 from limit switches 47, 48 to the other terminals of coils 56a, 57a respectively.

A common'line 63a connects conductor 530 through lines 4%, 51b to the other side of switches 47, 48 respectively.

Line 64 extends from rectifier 59 to lines 64a, 64b connected through resistances 65a, 65b to plates of condensers 66a, 6612, the other plates of which are connected to lines 49a, 51a respectively.

Energization of either coil 56a or 57a simultaneously opens a switch'67b or 67a in the circuit of the other coil.

This circuit operates as follows:

Assuming that the tension is too high, limit switch 47 will be closed. This will energize relay 56a to close switch 56, operating motor 44 in such a direction as to in- 4. crease the transmission ratio of transmission 28 to speed up the rate of feed of the thread. At the same time, condenser 66a is charged.

Now, when the tension is reduced and switch 47 opens, the connection between line 53c and coil 56a is broken. The charged condenser 66:: is disconnected from conductor 53c and begins to discharge through coil 56a, thus maintaining a current flow through the coil and keeping switch 56 closed until the condenser is substantially discharged, so that the motor continues to run. The period of discharge depends generally on the amount of current fed to coil 56a and the time constant of the discharge circuit formed by the condensor 66a and the series-connected resistances a, 61 and can be adjusted by knob 55.

Since energization of coil 56a opens switch 67b, coil 57a cannot be energized until coil 56a is released, even if switch 48 is closed.

Thus the motor will run inone direction for a predetermined time, no matter how short the time of closure of the limit switch may be. This reduces hunting and maintains the tension bar nearer to the middle of its range.

Closure of switch 48 produces, in the same manner, energization of coil 57a for a predetermined time to turn the motor in the opposite direction to increase the tension.

While I have described herein one embodiment of my invention, I wish it to be understood that I do not intend to limit myself thereby except within the scope of the claim hereto or hereinafter appended.

I claim:

1. In a Warp loom having a warp beam from which threads are withdrawn and having a variable-speed driving mechanism connected to the warp beam, a motor connected to said driving mechanism to vary the speed thereof, tension responsive means in the path of the withdrawn threads includin. a part movable in opposite directions through a range as tension varies, and means connected to said tension responsive means for connecting said motor to a current source for turning it in opposite directions thereby increasing or decreasing the speed of ,said driving mechanism as the movable part of said tension responsive means reaches one or the other end of said range, respectively, said connecting means including timing means to maintain connection of said electric motor to the current source for a predetermined time at each operation thereof, operation of said motor tending to move said part towards the other end of said range.

References Cited UNITED STATES PATENTS 1,709,616 4/1929 Goodwin 3l86 2,348,090 5/1944 Otto 318-6 X 2,353,639 7/1944 Berthold et a1. 318-6 X 2,896,140 7/1959 Fuge 3l 86 2,903,635 9/1959 Brooke et al 3l8--6 3,179,863 4/ 1965 Corey 318-6 ORIS L. RADER, Primary Examiner.

T. LYNCH, Assistant Examiner. 

1. IN A WRAP LOOM HAVING A WRAP BEAM FROM WHICH THREADS ARE WITHDRAW AND HAVING A VARIABLE-SPEED DRIVING MECHANIZM CONNECTED TO THE WRAP BEAM, A MOTOR CONNECTED TO SAID DRIVING MECHANISM TO VARY THE SPEED THERE, OF TENSION RESPONSIVE MEANS IN THE PATH OF THE WITHDRAWN THREADS INCLUDING A PART MOVABLE IN OPPOSITE DIRECTIONS THROUGH A RANGE AS TENSION VARIES, AND MEANS CONNECTED TO SAID TENSION RESPONSIVE MEANS FOR CONNECTING SAID MOTOR TO A CURRENT SOURCE FOR TURNING IT IN OPPOSITE DIRECTIONS THEREBY INCREASING OR DECREASING THE SPEED OF SAID DRIVING MECHANISM AS THE MOVABLE PART OF SAID TENSION RESPONSIVE MEANS REACHES ONE OR THE OTHER END OF SAID RANGE, RESPECTIVELY, SAID CONNECTING MEANS INCLUDING TIMING MEANS TO MAINTAIN CONNECTION OF SAID ELECTR MOTOR TO THE CURRENT SOURCE FOR A PREDETERMINED TIME AT EACH OPERATION THEREOF, OPERATION OF SAID MOTOR TENDING TO MOVE SAID PART TOWARDS THE OTHER END OF SAID RANGE. 